The document discusses several diseases that affect tea plants, including their symptoms, causal organisms, and methods of spread and management. It describes blister blight caused by Exobasidium vexans which forms blisters on leaves and stems. Grey blight caused by Pestalotia theae forms spots on leaves with black dots. Twig dieback caused by Macrophoma theicola results in browning and drooping leaves and dying branches. It also discusses various root diseases like brown root rot, black root disease, and Armillaria root rot, and their symptoms and management through removal of infected plants and soil fumigation. Red rust caused by the algal parasite Cephaleuros myco
Use of mutants in understanding seedling development.pptx
Diseases of Tea - Symptoms, Pathogenic characters and their Management
1. PAT 301 - DISEASE OF FIELD AND
HORTICULTURAL CROPS AND THEIR
MANAGEMENT (1+1)
DISEASES OF TEA
Presented By…
Guhan.C, B.Sc.(Hons).Agri,
Id no : 2018033029,
JKKMCAS, Erode, .
2. Name of the Disease Causal Organism
Blister Blight Exobasidium vexans
Grey Blight Pestalotia theae
Horse hair blight Marasmius crinisequi
Twig Dieback / Stem Canker Macrophoma theicola
Brown root disease Fomes lignosus
Black root disease Rosellina arcuta
Red root disease Poria hypolateritia
Armillaria root rot Armilliaria mellea
Red Rust Cephaleuros mycoides
Crop : Tea
Scientific Name : Camellia sinensis
Family : Theaceae
3. Blister Blight - Exobasidium vexans
Symptoms :
Small pale pinkish spots on leaves.
Upper surface of the spot become light green and depress into a
shallow cavity.
Lower surface correspondingly forming blister like swelling covered
by white growth of fungus.
Later stage blister turns dark brown and shrinks to flattened patch.
In stem, spots without blisters are formed and damages stem, leaves
and bud wither.
4.
5. Pathogen :
Sexual spores – Basidiospores
Asexual spores – Conidia
Conidia causes earlier infection.
Basidia causes drying of leaf.
Elliptical, bicelled conidia are born at terminal end of hyphae.
Hyphae aggregates and seen as mass.
6. Mode of spread :
Primary spread : Basidiospores from infected seedlings from
abandoned nursery.
Secondary spread : Basidiospores from infected plants.
Management :
Removal of affected leaves and shoots by pruning and destruction of
the same have been recommended.
Spraying of Bordeaux mixture or Copper Oxy Chloride 0.1%.
A mixture of 210g of Copper oxy Chloride + 210g of nickel chloride
per ha sprayed at 5 days interval from June to September and October
to November
Spray Tridemorph at 340 and 560 ml/ha is satisfactory under mild and
moderate rainfall conditions.
7. Grey Blight - Pestalotia theae
Symptoms :
Minute brownish spots on older leaves, soon turn grey.
Spots are irregular and have fine concentric lines.
Black dots of acervuli seen on older spots.
Leaves distorted and die back symptom appears.
8. Pathogen :
Conidia produced inside the black acervuli amidst sterile setae.
Conidiophores hyaline, short and simple and bear five celled
conidia.
The middle three celled are dark coloured while the end cells are
hyaline with 3-5 slender elongated appendages at the apex of the
spore.
9. Mode of spread - conidia from infected plants.
Management :
Avoid plant stress.
Grow tea bushes with adequate spacing to permit air to
circulate and reduce humidity and the duration of leaf wetness.
Spray Copper Oxy Chloride or Bordeaux mixture 0.1% during
winter season and Summer season.
10. Twig Dieback / Stem Canker - Macrophoma theicola
Symptoms :
The first symptoms include browning and drooping of affected leaves.
As the disease spreads into the shoots, they become dry and die.
The entire branch can die from the tip downward.
Dying branches often have cankers—shallow, slowly spreading lesions
surrounded by a thick area of bark.
11. Management :
Plant in well draining, acidic soils.
Remove diseased twigs by cutting several inches below cankered
areas and disinfecting them.
Spray appropriate protective fungicides during periods of wet
weather or natural leaf drop to protect leaf scars from infection.
12. Horse hair blight - Marasmius crinisequi
Symptoms :
Black fungal threads resembling horse hair are attached to upper
branches and twigs by small brown discs.
The fungus penetrates and infects the twigs from the discs and
produces volatile substances that cause rapid leaf drop.
Management :
Remove a and destroy all crop
debris from around plants.
Prune out infected or dead
branches from the plant canopy.
13. Brown root rot - Fomes lignosus
Symptoms :
The roots of the tea bush are encrusted with a mass of earth and small
stones cemented to the root by the mycelium.
Mode of spread - Rhizomorph and
root contact.
14. Black root disease - Rosellina arcuta
Symptoms :
Black strands adhere to the roots as loose cob – webby mass.
Star like sheets of white mycelium on the collar region.
Mode of spread - Rhizomorph and root contact.
15. Red root disease - Poria hypolateritia
Symptoms :
Flat, black, rhizomorph on infected portion.
Branched markings on the surface of the wood.
Root mottled appearance of red and white.
Bark softened and wood discoloured as
bluish black.
16. Armillria root rot - Armillaria mellea
Symptoms :
Bushes wilt and turn chlorotic, affect collar region; Bark cracks.
Sheets of creamy coloured mycelium accompanied by flattened
brown rhizomorph.
Sporophores produced on collar region, death of whole plant.
17. Pathogen :
Flattened brown rhizomorphs are produced.
Basidiospores from the sporophore infect the host.
18. Management of Root diseases:
Removal and destruction of infected plant.
Clean cultivation with out fallen leaves
Dig a drench around the infected bush to provide sunlight in the
drench which prevent the spread of mycelium.
Soil fumigation is the best method.
Application of Vepam and Metham Sodium 20-25cm apart from
collar of root to avoid phytotoxicity.
19. Red rust - Cephaleuros mycoides
Symptoms :
It is an algal parasitic or epiphytic.
Orange yellow, roughly circular patch on the upper surface of the
leaf.
The penetrating filament may extend laterally between epidermis
and adjacent layer.
20. Pathogen :
The algae produces sporangia on sporangiophore.
Sporangia produce numerous zoospores.
5-8 sporangia are formed on each vesicle.
Zoospores are involved in the disease spread.
21. Mode of spread - zoospores from infected plants.
Management :
Avoid plant stress.
Avoid poorly drained sites.
Promote good air circulation in the plant canopy to reduce
humidity and duration of leaf wetness.
Removal of infected portions by spraying of Bordeaux mixture.
Destruction of affected plant portions.
Improving the nutrient status of the soil by application of NPK.